Quantitative perfusion is primarily hampered by inaccuracies in measurements of cerebral blood volume (CBV). This is due to a combination of partial volume artifact and nonlinearity in the response to contrast agent concentration. Methods will be developed to obtain an independent whole brain measurement of CBV with a contrast infusion technique. We have recently purchased SENSE hardware and software for the MRI scanners at our institution so will modify the perfusion pulse sequence to take advantage of SENSE to reduce susceptibility artifacts in our images, Post-processing of blood flow and volume measurements will be developed using Statistical Parametric Mapping (SPM) techniques in normal subjects. Each subject's 3D cerebral blood flow (CBF) and CBV map will be coregistered to a common brain atlas, and a database of normal perfusion and blood volume will be compiled. Once these methods are implemented, these techniques will be extended to the study of patients with diagnosed dementias. Specifically, CBF and CBV will be compared to age and gender matched controls using both ROI and voxel by voxel statistical analyses such as SPM.